SYNTHETIC PHASED-ARRAYS FOR INTRALUMINAL IMAGING OF CORONARY-ARTERIES

A 64-element, high efficiency, ceramic piezoelectric array transducer operating at 20 MHz has been constructed for ultrasonic intraluminal i maging. The array is mounted on the surface of a 1,2 mm diameter cathe ter appropriate for coronary artery applications. Integrated into the catheter tip is a custom analog chip set permitting complete data capt ure from the array. That is, on each firing any combination of array e lements can be selected independently as transmitter or receiver. Usin g data acquired in this way, a complete phased array aperture (i,e., i ndependent transmit and receive apertures) can be synthesized. Reconst ruction hardware based an a custom application specific integrated cir cuit (ASIC) has been designed and built to produce real-time images. B eam forming coefficients are derived using an optimal filtering approa ch accounting for the circular geometry of the array. Simulated and me asured beam patterns for this system are compared. In addition, images of coronary anatomy acquired with the real-time system are displayed demonstrating the marked image quality improvement compared to previou s synthetic aperture intraluminal systems.